Influence of Crosslinking Method on the Properties of Natural Rubber Mixtures

Abstract

The most important stage in the rubber processing technology is vulcanization / crosslinking, which confers mechanical and thermal stability to rubbers. During crosslinking, rubber molecules with chain configuration are linked by chemical bridges / bonds, and the rubber mass turns from its plastic mass into an elastic one. This is normally done by sulphur and accelerator for general purpose rubbers. The chemistry of vulcanization is complex and the resulting crosslinks may be mono-, di-, tri-or higher poly-sulphides, with a proportion which is among others largely determined by the vulcanization system, the cure time and the temperature. These compounds and their reaction products could be responsible for cytotoxicity and allergycausing compounds, such as nitrosamines and nitrosatable materials. For these reasons, the aim was to eliminate or reduce toxic ingredients in elaborating and developing crosslinking technologies for natural rubber mixtures, so that the resulting materials may be used in the pharmaceutical or food industry, as well as in manufacturing other rubber goods (toys, various components for footwear, rubber plates, seals and hoses for various purposes, etc.). This paper presents a study on the influence of the vulcanization method on the characteristics of a natural rubber blend. The tested methods have been: (1) with sulphur and vulcanization accelerators, (2) with benzoyl peroxide in the presence of a polyfunctional monomer. Modification of characteristics was analysed depending on the crosslinking method.

Effect of co‐agents on adhesion between peroxide cured ethylene–propylene–diene monomer and thermoplastics in two‐component injection molding

“…Therefore, reversion index after 60 min was evaluated at 180 °C for EPDM without co‐agents (C0) and with the highest co‐agent concentrations of TAC and TMPT according to eq. () as these indicate the highest and lowest reversion: where and are maximum torque and torque after 60 min, respectively.…”

Degradation by Electron Beam Irradiation of Some Elastomeric Composites Sulphur Vulcanized

“…Five types of composites containing natural rubber and plasticized starch were obtained based on the recipes presented in Table 2 . The polymeric composites were obtained as in our previous work [ 20 ] and cross-linked using sulfur in the presence of the four combinations of vulcanization accelerators.…”

“…The compatibilizer maleated NR (NR-g-MA) was obtained by roll mixing 100 phr of natural rubber (NR) with 5 phr of maleic anhydride for synthesis and 0.75 phr of perkadox 40. The resulting mixture was kept at a temperature of 160 °C for 30 min and then used as such [ 20 ]. Plasticized starch was obtained based on starch, water, and glycerine in the proportions of 50%, 20%, and 30%, respectively.…”

“…The obtained plates were vulcanized using a hydraulic press at a temperature of 165 °C and a pressure of 150 Mpa. The vulcanization time was determined with the Monsanto rheometer [ 20 ].…”